The most common reason for replacement of direct resin restorations is recurrent (secondary) caries caused by cariogenic bacteria such as Streptococcus mutans at the gingival tooth- restoration interface. It is estimated that the cost of replacing resin restorations is in the billions of dollars worldwide and is increasing annually. A novel two-fold approach is proposed wherein more sensitive parameters and techniques will be used to: 1] identify the most effective method of biofilm removal that is least destructive to the surfaces of experimental restorative resins, and 2] determine changes in the nanoscale topography of the resins due to the attachment and growth of Streptococcus mutans (UA159) biofilms. This approach is unique because it will provide a detailed understanding of the 3-dimensional nanoscale topography of restorative resins and of the 3-dimensional structures of S. mutans biofilms and biofilm components that can form on restorative resins. The knowledge gained from the proposed research will be the first step toward the development of innovative modifications to the topography of restorative resins that can minimize oral biofilm formation. In the long-term, such strategies will reduce the incidence of recurrent caries and curtail the need for subsequent replacement of restorations, thereby improving oral health and realizing significant cost savings in oral healthcare. PUBLIC HEALTH RELEVANCE: The cost of replacing direct resin restorations due to recurrent caries is estimated to be in the billions of dollars and is increasing annually. The knowledge gained from the proposed research will provide the fundamental information necessary for the development of innovative surface modifications that minimize oral biofilm formation on restorative resins. It is also anticipated that the proposed project will benefit pre-doctoral dental students and undergraduate dental hygiene students by exposing them to innovative research at a non- research intensive college in the hopes that they will consider a career in dental education or dental research, which they might otherwise have not considered.